Noninvasive epicardial and endocardial electrocardiographic imaging of scar-related ventricular tachycardia

Abstract

Background The majority of life-threatening ventricular tachycardias (VTs) are sustained by heterogeneous scar substrates with narrow strands of surviving tissue. An effective treatment for scar-related VT is to modify the underlying scar substrate by catheter ablation. If activation sequence and entrainment mapping can be performed during sustained VT, the exit and isthmus of the circuit can often be identified. However, with invasive catheter mapping, only monomorphic VT that is hemodynamically stable can be mapped in this manner. For the majority of patients with poorly tolerated VTs or multiple VTs, a close inspection of the reentry circuit is not possible. A noninvasive approach to fast mapping of unstable VTs can potentially allow an improved identification of critical ablation sites. Methods For patients who underwent catheter ablation of scar-related VT, CT scan was obtained prior to the ablation procedure and 120-lead body-surface electrocardiograms (ECGs) were acquired during induced VTs. These data were used for noninvasive ECG imaging to computationally reconstruct electrical potentials on the epicardium and on the endocardium of both ventricles. Activation time and phase maps of the VT circuit were extracted from the reconstructed electrograms. They were analyzed with respect to scar substrate obtained from catheter mapping, as well as VT exits confirmed through ablation sites that successfully terminated the VT. Results The reconstructed reentry circuits correctly revealed both epicardial and endocardial origins of activation, consistent with locations of exit sites confirmed from the ablation procedure. The temporal dynamics of the reentry circuits, particularly the slowing of conduction as indicated by the crowding and zig-zag conducting of the activation isochrones, collocated well with scar substrate obtained by catheter voltage maps. Furthermore, the results indicated that some reentry circuits involve both the epicardial and endocardial layers, and can only be properly interpreted by mapping both layers simultaneously. Conclusions This study investigated the potential of ECG-imaging for beat-to-beat mapping of unstable reentrant circuits. It shows that simultaneous epicardial and endocardial mapping may improve the delineation of the 3D spatial construct of a reentry circuit and its exit. It also shows that the use of phase mapping can reveal regions of slow conduction that collocate well with suspected heterogeneous regions within and around the scar.

Model-Based Feature Augmentation for Cardiac Ablation Target Learning From Images

“…The work by Li and He [12] solves this inverse problem by means of heart-model parameters (onset activation location) and was further extended [13] and validated on rabbits [14] and swines [15], [16]. More recently, [17] was able to reconstruct re-entry circuits to correctly reveal both epicardial and endocardial origins of activation, consistent with locations of exit sites confirmed from the ablation procedure. Nevertheless, while it is useful in capturing and analysing global activation patterns, it still has limitations to assess the local abnormal ventricular activities (LAVA) like those studied here which serve as ablation targets for cardiac arrhythmia treatment.…”

Electrocardiographic imaging for cardiac arrhythmias and resynchronization therapy

“…Several studies have validated the use of ECGi mapping for catheter ablation in patients with PVC/VT. 21 , 50 , 59 , 63 The localization of the VT and PVC pacing sites by non-invasive electrophysiological mapping using 120 21 , 59 , 63 or up to 208 body surface electrodes 50 prior to the invasive procedure was shown to be correlated with the results from the invasive mapping system CARTO.…”

2019 APHRS expert consensus statement on three‐dimensional mapping systems for tachycardia developed in collaboration with HRS, EHRA, and LAHRS

“…Assessment of deeper tissue characteristics may be enhanced with the addition of unipolar signal amplitude . Epicardial, intramyocardial, and ECG imaging recordings have demonstrated the potential 3D complexity of reentry circuits, which may pass deep to endocardial contact catheters.…”